Modern electronic file systems typically store files in a hierarchical tree structure. Each node of the tree is considered a folder that contains one or more files. Typically, in such electronic file systems the location of an item is limited by the organization defined the file system. For example, in many file systems each file is located in one (and only one) folder. This means that file lifetime and file organization are conflated. That is, a file can exist only while it has a location organized relative to other files or folders. In addition, a file cannot be placed in multiple organizations. This means that if a user wishes to view a file in multiple folders, for example, the user must make multiple copies of the file. This is both tedious and error-prone for the user, as well as wasteful of storage space.
In addition, when performing a drag/drop operation, it is not always clear to the user what action is going to be taken upon completion of the drag/drop operation. It can be even more confusing when multiple files for dragging/dropping have been selected together.